In an exclusive interview from a California prison, Don Bohana, the man convicted of the 1994 murder of girlfriend Dee Dee Jackson, Tito Jackson's ex-wife, told ABC News' "20/20" that he'd sooner die in prison than admit to killing her.

"Hell will freeze over before I admit I did something I didn't do," he said.

Bohana, now in his 80s and having spent 19 years in prison, is preparing to petition the Los Angeles County District Attorney's Office 2-year-old Conviction Review Unit in hopes of having his conviction overturned.

In 1994, he was a 59-year-old divorcee when he met 39-year-old Delores "Dee Dee" Jackson. He lived an upscale lifestyle, owning luxury cars, a plane and a boat. An L.A. businessman, Bohana was handsome, wealthy and successful, making his fortune running hospitals and insurance companies.

He hobnobbed with politicians and celebrities but was also community-minded, opening a Denny's in Watts, the first sit-down restaurant in the neighborhood since the riots of 1965.

Dee Dee Jackson was a divorcee herself, after ending her marriage to Tito Jackson, a member of the famous Jackson 5 and the father of her three sons, Taj, TJ and Taryll.

A hot August night in Los Angeles

On the night of Aug. 26, 1994, she was with Bohana at his home in the exclusive Ladera Heights neighborhood of Los Angeles County. The two had been dating for eight weeks. It was 11 p.m. and the two were alone, finishing a late dinner and imbibing. Bohana was drinking wine; Dee Dee Jackson, rum and Coke.

"It was very, very hot, unusually hot in L.A. at the time. ... We'd go out, sit by the pool, have a couple of drinks. Delores would sometimes have a cigarette. It's very romantic," he said.

Hours later, around 3:30 a.m., though, Bohana was on the phone with a 911 operator. As he told "20/20", the two had ended up in the hot tub. Dee Dee Jackson, he said, then swam over, back and forth, in the pool when he noticed that she seemed to be in trouble. Bohana says that after a series of desperate attempts, he managed to get her out of the deep end of the pool -– 15 feet of water.

"I jumped in, put my arms around her and then flipped her out of the pool," he said. "At that time, I started doing CPR on her."

After he called 911, emergency medical personnel arrived. An unresponsive Dee Dee Jackson was transported to a hospital but doctors later pronounced her dead.

An autopsy report showed that her blood alcohol level was three times the legal limit for driving. The report also noted numerous bruises and scrapes on her face and body that Los Angeles County coroner Dr. David Posey described as the result of "blunt force trauma" and labeled "non-accidental."

The Jackson family, including ex-husband Tito Jackson and Dee Dee Jackson's sons, had questions immediately. They did not believe Dee Dee Jackson had accidentally drowned in the pool because, they say, she was terrified of water and could not swim.

"I'll go to my grave saying that she could swim because Delores could swim," he told "20/20."

'Delores could swim'

He told the press after her death that Dee Dee Jackson had been comfortable swimming in his pool, noting that she kept several swimsuits at his house. Also in the police report, Taj Jackson said his mother had told him "she was trying to learn to swim and Mr. Bohana was teaching her."

Bohana also told the press that the bruises found on her were the result of his desperate, drunken efforts to rescue her with a pool pole.

In November 1994, coroner Posey ruled the manner of her death "undetermined," and for two years, the district attorney's office took no action.

So the powerful Jackson family hired lawyer Brian Oxman who waged a media campaign to get Bohana charged in Dee Dee Jackson's death. He also filed a wrongful death suit against Bohana on behalf of the three sons. In the lawsuit, he claimed Bohana was bankrupt and deeply in debt. Oxman theorized that Bohana had turned to Dee Dee Jackson for help, she had become furious that he'd asked her to bail him out -- and a fight had soon followed.

However, Lori Jones, the deputy district attorney who built the case that led to Bohana's being charged, says there is no proof of that theory.

Oxman also claimed police reports showed Bohana's having a history of violence against women and told the press that police had responded at least a dozen times to 911 calls made from his house by past girlfriends. But, the lead investigator told "20/20" that police records show that there were only calls about noise complaints and that none of Bohana's past girlfriends said he had been abusive.

About two years after Dee Dee Jackson's death, Lori Jones was a newly assigned, aggressive, young prosecutor on the case. She recognized the key to charging Bohana was getting Posey, the coroner, to change his "undetermined" opinion on the manner of death. So, according to Jones, she reinvigorated the probe, sending police back to the pool. Her investigators, including water rescue experts, doubted Bohana's account of Dee Dee Jackson's injuries.

"When we got all of those additional reports, we took it back to the L.A. county coroner (Posey), and he changed his opinion," she said.

Donna Bohana

Don Bohana is seen here standing next to a plane in this undated family photo.

The criminal trial begins

In September 1996, two years after his initial ruling, Posey changed his opinion on the manner of death from "undetermined" to "homicide." And, in March 1997, almost three years after Dee Dee Jackson drowned, Bohana was charged with second-degree murder. He pleaded not guilty.

Baden, a Fox News consultant and former New York City chief medical examiner with decades of experience, reviewed Posey's original autopsy report. He inspected photos of Dee Dee Jackson's bruises and walked the pool with Bohana.

"It was clear to me that this was a typical, innocent, accidental drowning in which two people were drinking a lot and one of them drowned," Baden told "20/20." "I think there's no evidence of homicide."

Baden said some of the bruises noted on Dee Dee Jackson's face and body were "trivial injuries, often caused by rescue attempts [and] entirely consistent with the attempts to get her out of the pool." He also said that many other bruises were consistent with something else.

"She had a very diseased liver from drinking," Baden said. "She's gonna bump into things and get a bruise when others might not have."

During the trial, which began in June 1998, an aquatics expert testified that it's more likely that a water rescuer will receive more injuries than the person being rescued. The prosecutor then pointed out that Dee Dee Jackson, not Bohana, bore bruises.

Posey testified that Dee Dee Jackson's bruises were signs that Bohana severely beat her before she drowned in the pool.

The trial lasted for three weeks. And yet, as the trial progressed, Baden, the defense's star forensic pathologist, never testified.

Where is Dr. Michael Baden?

In fact, Braun didn't call a single expert witness. Instead, he had Bohana testify, and by all accounts, he did a poor job on the stand. Bohana told "20/20" that he didn't have any professional preparation -- something Braun disputes.

When the jury returned with a verdict, Bohana was convicted of second-degree murder in November 1998 and sentenced to 15 years to life. His deepest anger, he said, is toward the defense mounted by Braun, who'd left Baden off the stand.

"He just screwed me all the way," Bohana said.

Braun, however, told "20/20" that Baden would have been a weak witness and that Bohana was to blame for the courtroom loss.

"To be honest about the case, the worst witness was Mr. Bohana," he said.

Braun said his trial strategy was to damage the credibility of the prosecution's witnesses during cross-examination.

"It's always better to get what you want out of a prosecution witness than your own witness," Braun said.

In 2002, Bohana appealed the conviction on the grounds that Braun had provided ineffective counsel. An appeals judge rejected Bohana's claim, ruling that Braun's trial strategy was "reasonable." Bohana has since been denied parole four times. The first parole denial was on March 23, 2007.

Bohana said he also suspects money was the reason behind Braun's decision not to call Baden. At the time of the trial, Bohaha was behind in his payments to Braun. According to a sworn affidavit filed by Bohana's brother, Braun called him the night before trial, saying: "It is not wise to have an attorney starting trial angry about nonpayment of his fee."

Braun told "20/20" he never made that statement.

"I didn't like the fact that he stiffed me," he said. "But I wasn't going to pull any punches on a murder case."

Donna Bohana uncovers some news reports

With her father languishing behind bars, Donna Bohana, a realtor in Malibu, California, is combing through every document in the case.

She uncovered old news accounts revealing that as prosecutors were relying on coroner Posey to enable them to indict Don Bohana, another prosecutor named Stephen Kay from the same L.A. County district attorney's office was calling him a "fraud."

Kay, a highly regarded veteran prosecutor who has since retired, said he had investigated Posey's background before he testified as a private consultant for the defense in a 1996 trial opposite Kay.

Kay said he'd found that while Posey had experience as a hospital pathologist, his background as a coroner in criminal cases was limited and he had been a part-timer at the L.A. County coroner's office for less than a year.

"He just dabbled in autopsies," Kay said. He also said he would have told Jones, the deputy district attorney whose investigation led to Bohana's indictment, about, what he calls, Posey's lack of qualifications if he'd been asked.

Jones told "20/20" she didn't remember hearing anything negative about Posey at that time. When asked whether hearing about it now concerned her, Jones said, "Sure, it would concern me, but it's not causing me to lose confidence in the outcome."

Posey speaks to '20/20'

At trial, Posey testified that he had always suspected that Dee Dee Jackson's death was a homicide.

He says he changed his opinion from "undetermined" to "homicide" about two years after she died because of his visits to Bohana's pool, his experience as a lifeguard and because someone in the district attorney's office had told him they had an expert who'd confirmed his opinion that Dee Dee Jackson's death was a homicide.

But Posey admitted on the stand that he'd never spoken to that expert nor read his report before changing that opinion.

"20/20" wanted to speak with Posey about the case. Numerous requests for an interview went unanswered so "20/20" caught up with Posey on the street.

While Posey said the name "Dee Dee Jackson" was vaguely familiar, he said he could not recall the testimony.

Even with Bohana about to petition the review unit regarding his conviction, his family remains in anguish that the octogenarian may die behind bars. He told "20/20" Dee Dee Jackson's death still pains him to this day.

"I am responsible and it just pains me very much," he said. "Had I not been drinking, there's not a doubt that I would have been able to save her."